using System;
using System.Text;
using System.Linq;

class Utils
{   
	// Copied from https://www.codeproject.com/Articles/36747/%2FArticles%2F36747%2FQuick-and-Dirty-HexDump-of-a-Byte-Array
	public static string HexDump(byte[] bytes, int bytesPerLine = 16)
	{
		if (bytes == null) return "<null>";
		int bytesLength = bytes.Length;

		char[] HexChars = "0123456789ABCDEF".ToCharArray();

		int firstHexColumn =
			8                   // 8 characters for the address
			+ 3;                  // 3 spaces

		int firstCharColumn = firstHexColumn
			+ bytesPerLine * 3       // - 2 digit for the hexadecimal value and 1 space
			+ (bytesPerLine - 1) / 8 // - 1 extra space every 8 characters from the 9th
			+ 2;                  // 2 spaces 

		int lineLength = firstCharColumn
			+ bytesPerLine           // - characters to show the ascii value
			+ Environment.NewLine.Length; // Carriage return and line feed (should normally be 2)

		char[] line = (new String(' ', lineLength - Environment.NewLine.Length) + Environment.NewLine).ToCharArray();
		int expectedLines = (bytesLength + bytesPerLine - 1) / bytesPerLine;
		StringBuilder result = new StringBuilder(expectedLines * lineLength);

		for (int i = 0; i < bytesLength; i += bytesPerLine)
		{
			line[0] = HexChars[(i >> 28) & 0xF];
			line[1] = HexChars[(i >> 24) & 0xF];
			line[2] = HexChars[(i >> 20) & 0xF];
			line[3] = HexChars[(i >> 16) & 0xF];
			line[4] = HexChars[(i >> 12) & 0xF];
			line[5] = HexChars[(i >> 8) & 0xF];
			line[6] = HexChars[(i >> 4) & 0xF];
			line[7] = HexChars[(i >> 0) & 0xF];

			int hexColumn = firstHexColumn;
			int charColumn = firstCharColumn;

			for (int j = 0; j < bytesPerLine; j++)
			{
				if (j > 0 && (j & 7) == 0) hexColumn++;
				if (i + j >= bytesLength)
				{
					line[hexColumn] = ' ';
					line[hexColumn + 1] = ' ';
					line[charColumn] = ' ';
				}
				else
				{
					byte b = bytes[i + j];
					line[hexColumn] = HexChars[(b >> 4) & 0xF];
					line[hexColumn + 1] = HexChars[b & 0xF];
					line[charColumn] = (b < 32 ? '·' : (char)b);
				}
				hexColumn += 3;
				charColumn++;
			}
			result.Append(line);
		}
		return result.ToString();
	}
	
	public static string RandomString(int length)
	{
		var random = new Random();
		const string chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
		return new string(Enumerable.Repeat(chars, length).Select(s => s[random.Next(s.Length)]).ToArray());
	}
}